The present invention generally relates to phacoemulsification handpieces for the removal of a cataract lens from an eye and is more particularly related to phaco tip apparatus for a phacoemulsification handpiece. A well known method for method for the removal of a cataract through a surgical incision in the eye is known as phacoemulsification. A handpiece for phacoemulsification generally includes an ultrasonic generator which is attached to a hollow needle which is vibrated and, when inserted into an eye, is capable of emulsifying an eye lens and aspiration thereof through a lumen in the needle. The needle is surrounded by a sleeve when inserted through an incision in the eye. The tip of the needle engages and emulsifies the cataract and a suction force is applied through the needle interior lumen to withdraw the emulsified cataract into the needle and out of the eye.
The sleeve protects the wound through which the needle is passed from contacting the needle which can become heated, and the sleeve further establishes an annular passage around the needle for providing an irrigation fluid to the eye, while at the same time cooling the needle.
Typically, the cornea or sclera incision is linear and has a length approximately to one-half the circumference of the sleeve in order to minimize fluid leakage from the incision, or wound, when the needle/sleeve is inserted therethrough.
A great number of sleeve designs have been proposed and a number of materials have been utilized in prior art sleeves. For example, U.S. Pat. No. 4,787,889 to Steppe et al, discloses a flexible sleeve made of a synthetic resin such as silicon rubber which is able to fold back or telescope when inserted through an incision. The problems with these prior art devices include collapsing of the flexible sleeve in the area of the wound by pressure from surrounding tissue. This collapsing of the sleeve blocks flow of the irrigation to the surgical site and around the vibrating needle, which can cause overheating and damage to adjacent tissue. Sleeves made out of metallic material, such as also described in the hereinabove referenced U.S. patent, do not allow collapse and, accordingly, allow a greater fluid leakage from the wound.
In order to minimize leakage from the wound past the sleeve, an elliptical sleeve has been proposed, for example, see U.S. Pat. No. 5,084,009. This collapsible, or compressible, sleeve is made with a shape matching the configuration of a surgical incision in order to minimize leakage between the exterior surface of the sleeve and the surgical incision. However, in order for the ultrasonic needle to exhibit a desired and vibratory motion, which is relatively free from damping, this elliptical sleeve must be prohibited from touching the needle during the operation.
During phacoemulsification procedures, the needle must be partially rotated and its angle of incident changed in order to effect complete phacoemulsification and removal of the lens. In these procedures, a soft sleeve, particularly one shaped to the size of the wound, may collapse, or deflect against the ultrasonic needle. When the sleeve is pushed against the rapidly vibrating needle, the needle and sleeve tend to overheat due to friction, which may damage delicate cornea or sclera tissue, particularly the corneal epithelium.
Also during phacoemulsification procedures, an emulsified lens particle may block the aspirating lumen. The blockage may be sufficient to require reversal of fluid flow through the lumen in order to dislodge the blockage. This interruption may cause undesirable pressure changes in the eye. Many equipment designs and methods have been derived in order to minimize the problems introduced by a blocked aspiration lumen. Among such designs is the use of a bypass port between the irrigation fluid in the sleeve and the aspiration lumen of the needle. Such a port enables irrigation fluid to be aspirated before it reaches the eye which may cause a surge in pressure in the eye.
Unfortunately, when such a bypass port is used in conjunction with a compressible sleeve, inadvertent closure of the port may occur.
The present invention is directed to a sleeve which shapes itself to the wound by pressure of surrounding tissue in order to minimize leakage of fluid therepast. In addition, internal structure of the sleeve maintains proper annular channel around the needle for passage of cooling fluid. Accordingly, the needle is prevented from touching the sleeve. In addition, the sleeve is attached to the phacoemulsification handpiece to enable angular motion of the needle within the sleeve so that the sleeve wound junction is not disturbed. Further structure is provided to prevent any closure of a bypass port as hereinabove noted.
Phaco tip apparatus in accordance with the present invention is suitable for a phacoemulsification handpiece having an ultrasonic drive assembly for emulsifying and aspirating a cataract lens through a cornea/sclera wound.
The subject phaco tip apparatus generally includes a needle having a tip, for emulsifying a cataract lens through a cornea/sclera wound, and lumen for aspirating emulsified lens. A compressible sleeve provides a means for establishing an annular passage around the needle and enabling the irrigation fluid to pass into an eye through the cornea/sclera wound while simultaneously cooling the needle.
A bypass port is disposed in the needle and beneath the comprisable sleeve for establishing fluid communication between the lumen and the annular passage in order to enable irrigation fluid to pass into the needle lumen upon clogging, or blocking of the tip. Thus, the bypass port protects, or lessens, any usage of fluid and/or fluid pressure in the eye.
The compressible sleeve includes a wall configuration which provides a means for controlling compression of the sleeve in order to cause the compressible sleeve to shape and conform to the cornea/sclera wound and limit fluid egress from the wound. That is, the construction of the compressible sleeve wall enables the sleeve, upon compression by tissue subtending the wound, to fill, or contact, all of the wound surface so that no gaps are established which can permit the leakage of fluid.
In addition, a hub means may be provided for attaching the compressible sleeve to the handpiece and for enabling the needle to be angularly displaced within the compressible sleeve means. Thus, once the compressible sleeve is conformed to the wound shape, it need not be disturbed by subsequent manipulation of the needle which is necessary in order to properly emulsify and aspirate a cataract lens.
In one embodiment of the invention, the compressible sleeve includes a variation in wall thickness around the circumference of the compressible sleeve which may include two areas of the sleeve wall having greater thickness than adjoining areas in the sleeve wall. These two areas are preferably spaced apart from one another at about 180xc2x0 around the sleeve means circumference. Thus, when the compressible sleeve is inserted into a slit type cornea/sclera wound, the thicker portions of the wall are disposed at opposite ends of the slit and compression of the sleeve enables confirmation of the sleeve with all of the surrounding wound tissue including the ends of the slit.
Still more particularly, the two areas of greater wall thickness may include nodules which extend outward from the compressible sleeve means.
In another embodiment of the present invention, the sleeve may include a variation in wall density of the sleeve walls around the circumference of the sleeve. The variation in wall density preferably includes two areas of the sleeve having a lower density than adjoining areas of the sleeve wall, with the two areas of lower density being spaced apart from one another at 180xc2x0 around the sleeve means configuration.
In a manner as similarly described in conjunction with a wall having thicker areas, this lower density area enables a preferential compression of the sleeve and outward extension of the sleeve in the low density wall areas so that the sleeve can conform and contact with all of the tissue surrounding the slit wound.
Also, in accordance with the present invention, in order to limit compression of opposing walls of the compressive sleeve to prevent contact of the compressible sleeve with the needle, and undesired closure of the bypass port at least one depending member is provided. In addition to preventing contact of the compressible sleeve with the needle, and closure of the bypass port by the compressive sleeve, continued cooling of the needle is ensured at all times.
More particularly, two depending members having a length greater than the diameter of the needle, may be disposed within the compressible sleeve and are attached to opposing walls between the two wall areas of greater thickness, or lesser density.